This invention relates generally to devices for producing a gas such as used for the inflation of inflatable elements such as in the form of cushions or curtains included in vehicular inflatable restraint systems. More particularly, this invention relates to a flexible inflator such as may be readily conformed for placement in a variety of locations within a vehicle.
It is well known to protect a vehicle occupant using a cushion or bag, e.g., an “airbag cushion” that is inflated or expanded with a gas when a vehicle experiences sudden deceleration, such as in the event of a collision. Such airbag restraint systems normally include: one or more airbag cushions, housed in an uninflated and folded condition to minimize space requirements; one or more crash sensors mounted on or to the frame or body of the vehicle to detect sudden deceleration of the vehicle; an activation system electronically triggered by the crash sensors; and an inflator device that includes a gas generating composition or propellant the combustion of which produces or supplies a gas to inflate the airbag cushion. In the event of a sudden deceleration of the vehicle, the crash sensors trigger the activation system which in turn triggers the inflator device which begins to inflate the airbag cushion in a matter of milliseconds.
Various types or forms of such inflatable restraint systems have been developed or tailored to provide desired vehicle occupant protection such as based on either or both the position or placement of the occupant within the vehicle and the direction or nature of the vehicle collision, for example. In particular, driver and passenger inflatable restraint installations have found wide usage for providing protection to drivers and front seat passengers, respectively, in the event of head-on types of vehicular collisions. Driver and passenger inflatable restraint installations do not, however, generally provide as great as may be desired protection against vehicular impacts inflicted or imposed from directions other than head-on, i.e., “side impacts”. In view thereof, substantial efforts have been directed to developing inflatable restraint installations having particular effectiveness in the event of a side impact.
Inflatable curtain restraint devices are a relatively new development in the field of inflatable restraint systems. Generally, such inflatable curtain restraint devices are positioned within the vehicle frame along the ceiling adjacent the door frame of the vehicle. Typically such inflatable curtain restraint devices include an inflatable curtain designed to deploy over at least a portion of the door frame and/or window of a vehicle to cushion an occupant from impact with the door frame and/or window, particularly in the event of a side impact or rollover crash. Such inflatable curtain restraint devices also typically include an inflator device to provide an inflation fluid, typically in the form of a gas, to inflate the inflatable curtain. One such inflatable curtain restraint device is disclosed in U.S. Pat. No. 5,788,270 to H{dot over (A)}land et al., the disclosure of which is incorporated herein by reference.
Many types or forms of inflator devices have been disclosed in the art for use in inflatable restraint systems. One particularly common type of inflator device is commonly referred to as a pyrotechnic inflator. In such inflator devices, gas used in the inflation of an associated inflatable element is derived from the combustion of a pyrotechnic gas generating material or propellant. However, the combustion efficiency, and therefore, the effectiveness of the inflatable restraint system, can be compromised if the gas generating material or propellant is exposed to moisture or non-collision related shock or impact. In practice, therefore, the gas generating material is typically protected from moisture and shock by enclosing the material within a separate container or housing.
Pyrotechnic inflator devices, such as are used for the inflation of inflatable curtains, are commonly cylindrical in shape and typically have a length that is greater than a diameter of the inflator device. In practice, the length/diameter ratios of such inflator devices have been limited or restricted by the general need or desire to ensure relative uniformity in ignitability over the length of the inflator device. In particular, it has proven difficult to attain ignition of an extended length of pyrotechnic gas generant or propellant material in a uniform manner while in an assembly of small diameter. Moreover, inflatable restraints such as inflatable curtains which are commonly designed to provide protection over an extended area typically need to be rapidly inflated over relatively extended lengths, as compared to common front impact inflatable restraint devices. The provision of inflation gas produced by the combustion of pyrotechnic gas generant or propellant materials along extended lengths in a desirably uniform and rapid manner can be particularly challenging to achieve.
Many of today's vehicles have a rounded or contoured chassis to promote aerodynamic performance and improved fuel efficiency. As result, the locations within the vehicle wherein inflatable curtain restraint devices are typically disposed are correspondingly contoured or curved. Thus, the inflatable curtain restraint device including the inflator device, and, preferably, the individual components thereof, are advantageously flexible to allow the inflator device to conform to the contours of a wide variety of vehicles.
In addition to the above challenges, manufacturing, assembly and cost reduction benefits continue to be major objectives sought to be achieved in the design and development of modern vehicles and the assemblies and components included therewithin.
Thus, there is a need and a demand for a flexible inflator device that may be readily conformed to a variety of locations within a variety of vehicles that is easier and less expensive to manufacture and assemble. There is also a need and a demand for an inflator device that exhibits sufficient stability over the life of the system within a vehicle. There is a further need and a demand for an inflator device proportioned for use with an inflatable curtain that provides efficient combustion of the propellant component and even inflation of the inflatable curtain. There is a still further need and a demand for an inflator device that is flexible and may be employed in a variety of vehicle sizes and types and/or in a variety of locations and orientations within a vehicle.